Receivers in a multiple receiver system occasionally suffer from faults such as poor calibration or hardware malfunction. If the fault goes uncorrected, then information may not be properly received by the multiple receiver system causing faulty voice and/or data communications. Accordingly, multiple receiver systems tend to employ fault detection methods to find these faults and permit timely correction thereof.
In a first example of a conventional fault detection method, a pilot signal is transmitted by a first radio system. The pilot signal is then received by a second radio system. The received pilot signal is processed by a second radio system receiver and then output to other components of the second radio system. The output power of the receiver in the second radio system, as a response to the pilot signal is then compared against the pilot signal transmit power from the first radio system. If a significant power difference exists between the pilot signal transmit power of the first radio system and the output power of the second radio system receiver as a result of the pilot signal, a fault is determined to exist in the second radio system. Problems with this approach for detecting a fault are that two radio systems are needed, one for transmitting a pilot signal and one for receiving the pilot signal. Additionally, extra energy is needed to generate a pilot signal solely for fault detection purposes. Furthermore, it may be difficult to determine which receiver system is faulty where there is more than one receiver system in the second radio system.
In a second example of a conventional fault detection method, only one radio system is used. In the second example of a fault detection system, a pilot signal is output by a first radio system. The pilot signal output is then received by the same radio system—the first radio system. The received pilot signal is then processed by a receiver in the first radio system. The output power of the first radio system receiver is then compared against the original pilot signal output power. If a significant difference in power exists between the output of the first radio system pilot signal and the output of the first radio system receiver, a fault is determined to exist in the first radio system. Problems associated with this approach are that extra energy may be needed to generate the extra pilot signal only for fault detection purposes. Additionally, it may be difficult to determine which receiver system is faulty where there is more than one receiver system in the first radio system.
In a third example of the conventional art, an uplink signal is received from a mobile unit by a first radio system. A receiver of the first radio system determines the power of the uplink signal received. If the received signal strength indicator (RSSI) value is below a set threshold, a fault may be determined to exist in the first system. A problem with this approach is that it may be difficult to determine which receiver system is faulty where there is more than one receiver system in the first radio system.